Solder alloy composition, its preparation method and uses in room-temperature rapid solid-state soldering
Disclosed herein are a solder alloy composition comprising Sn—Bi—In base solder particles. The Sn—Bi—In base solder particles is characterized by having an average diameter less than 10 μm, and the Sn—Bi—In base alloy comprises 12-22% of Sn, 33-43% of Bi and 45-55% by weight. Also disclosed herein is a method for producing the Sn—Bi—In base solder particles. The method mainly includes the steps of, sintering a mixture comprising tin (Sn), bismuth (Bi) and indium (In) at a designated weight ratio to produce a bulk alloy; dissolving the bulk alloy to produce an alloy solution; and subjected the alloy solution to ultrasonication at a first temperature of about 65-85° C. and then cooling at a second temperature of about 0-25° C., thereby produces the present Sn—Bi—In base solder particles.
1 . A method for producing solder particles of a Sn—Bi—In base alloy, comprising:
(a) preparing a mixture comprising tin (Sn), bismuth (Bi) and indium (In) to produce a bulk alloy, in which the bulk alloy has a melting point of about 60-65° C.;
(b) dispersing the bulk alloy of step (a) in an ethylene glycol solution containing polyvinylpyrrolidone (PVP) to produce an alloy solution;
(c) subjecting the alloy solution of step (b) to ultrasonication at a first temperature of about 65-85° C. for 10 to 150 minutes to produce a suspension; and
(d) cooling the suspension of step (c) to a second temperature of about 0-25° C. to produce the solder particles of the Sn—Bi—In base alloy;
wherein, each of the solder particles is less than 10 μm in diameter, and the Sn—Bi—In base alloy comprises 12-22% of Sn, 33-43% of Bi and 45-55% of In by weight.
2 . The method of claim 1 , wherein the Sn, Bi, and In are present in the mixture at a ratio of about 1:1:2 to about 1:3:5 by weight.
3 . The method of claim 2 , wherein the Sn, Bi, and In are present in the mixture at a ratio of about 1:3:3 by weight.
4 . The method of claim 1 , wherein the melting point of the bulk alloy of step (a) is about 62° C.
5 . The method of claim 1 , wherein in step (c), the ultrasonication is conducted at a frequency of 40 KHz and a power of 120 W for about 30 minutes.
6 . The method of claim 1 , wherein in step (c), the ultrasonication is conducted at a frequency of 40 KHz and a power of 120 W for about 60 minutes.
7 . The method of claim 1 , wherein in step (c), the ultrasonication is conducted at a frequency of 80 KHz and a power of 120 W for about 120 minutes.
8 . The method of claim 1 , wherein in step (c), the ultrasonication is conducted at about 75° C.
9 . The method of claim 1 , wherein in step (d), the suspension of step (c) is cooled by placing it in an ice bath until it reaches the second temperature of about 0° C.
10 . The method of claim 1 , wherein each of the solder particles of Sn—Bi—In base alloy is less than 10 μm in diameter.
11 . The method of claim 10 , wherein each of the solder particles of Sn—Bi—In base alloy is about 0.1 to 3 μm in diameter.
12 . The method of claim 10 , wherein each of the solder particles of Sn—Bi—In base alloy is about 1 to 6 μm in diameter.
13 . The method of claim 1 , wherein in step (a), the mixture further comprises Pb, Zn, or Ag.